An important point of using solar and wind together is that both devices have a totally different U-I characteristic. The voltage variation of a solar panel is slow but of a wind turbine can be very fast during wind gusts. If you charge a battery, you will always need a battery charge controller which prevents that the battery is overloaded when it is full.
If you use only a solar panel, you can use a simple device which separates the solar panel from the battery when the voltage is too high. The maximum open voltage of a solar panel is not that high that the electronics in the voltage controller will be damaged. If the battery voltage is reduced enough, the panel is connected to the battery again and charging continues. However, the open voltage of a wind turbine can be much higher and the voltage variation is much faster. So a voltage controller designed for a solar panel can normally not be used in combination with a wind turbine as you will blow up the electronics because of the high maximum open voltage. Another problem is that the wind turbine will run unloaded when it is disconnected from the battery and the rotor will therefore be very noisy.
Battery charge controllers for wind turbines normally have a dump load and the voltage controller guides that much power to the dump load that the charging voltage is maintained at the maximum allowable level. But a dump load makes the battery charge controller more expensive. But a battery charge controller with a dump load can also be used for a solar panel. The maximum power which can be dissipated in the dump load must be equal to the sum of the maximum power of wind turbine and solar panel together. On my website
www.kdwindturbines.nl you find a free manual of a 200 W, 27.6 V battery charge controller at the bottom of the menu KD-reports. The power of this device can be increased by connecting several 200 W dump load modules in parallel and using only one voltage controller.
